X-Git-Url: http://git.lttng.org/?a=blobdiff_plain;f=src%2Flttng-events.c;h=9f683db18f2274badbaeb37288d4843fc7c246e0;hb=99f52fcce5865809584c1e022bca1409702ea292;hp=34e5fe9d98e657aaba9de8cac0f250614b6eaff0;hpb=2dfda770cc6781ec372ee8dadd8eb4f6ab37375a;p=lttng-modules.git

diff --git a/src/lttng-events.c b/src/lttng-events.c
index 34e5fe9d..9f683db1 100644
--- a/src/lttng-events.c
+++ b/src/lttng-events.c
@@ -24,7 +24,6 @@
 #include <linux/file.h>
 #include <linux/anon_inodes.h>
 #include <wrapper/file.h>
-#include <linux/jhash.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
 #include <linux/dmi.h>
@@ -37,10 +36,13 @@
 #include <wrapper/types.h>
 #include <lttng/kernel-version.h>
 #include <lttng/events.h>
+#include <lttng/lttng-bytecode.h>
 #include <lttng/tracer.h>
+#include <lttng/event-notifier-notification.h>
 #include <lttng/abi-old.h>
 #include <lttng/endian.h>
 #include <lttng/string-utils.h>
+#include <lttng/utils.h>
 #include <ringbuffer/backend.h>
 #include <ringbuffer/frontend.h>
 #include <wrapper/time.h>
@@ -48,20 +50,27 @@
 #define METADATA_CACHE_DEFAULT_SIZE 4096
 
 static LIST_HEAD(sessions);
+static LIST_HEAD(event_notifier_groups);
 static LIST_HEAD(lttng_transport_list);
+static LIST_HEAD(lttng_counter_transport_list);
 /*
  * Protect the sessions and metadata caches.
  */
 static DEFINE_MUTEX(sessions_mutex);
 static struct kmem_cache *event_cache;
+static struct kmem_cache *event_notifier_cache;
 
 static void lttng_session_lazy_sync_event_enablers(struct lttng_session *session);
 static void lttng_session_sync_event_enablers(struct lttng_session *session);
 static void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler);
+static void lttng_event_notifier_enabler_destroy(struct lttng_event_notifier_enabler *event_notifier_enabler);
+static void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group);
 
 static void _lttng_event_destroy(struct lttng_event *event);
+static void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier);
 static void _lttng_channel_destroy(struct lttng_channel *chan);
 static int _lttng_event_unregister(struct lttng_event *event);
+static int _lttng_event_notifier_unregister(struct lttng_event_notifier *event_notifier);
 static
 int _lttng_event_metadata_statedump(struct lttng_session *session,
 				  struct lttng_channel *chan,
@@ -108,6 +117,17 @@ void lttng_unlock_sessions(void)
 	mutex_unlock(&sessions_mutex);
 }
 
+static struct lttng_transport *lttng_transport_find(const char *name)
+{
+	struct lttng_transport *transport;
+
+	list_for_each_entry(transport, &lttng_transport_list, node) {
+		if (!strcmp(transport->name, name))
+			return transport;
+	}
+	return NULL;
+}
+
 /*
  * Called with sessions lock held.
  */
@@ -178,6 +198,126 @@ err:
 	return NULL;
 }
 
+static
+struct lttng_counter_transport *lttng_counter_transport_find(const char *name)
+{
+	struct lttng_counter_transport *transport;
+
+	list_for_each_entry(transport, &lttng_counter_transport_list, node) {
+		if (!strcmp(transport->name, name))
+			return transport;
+	}
+	return NULL;
+}
+
+struct lttng_counter *lttng_kernel_counter_create(
+		const char *counter_transport_name,
+		size_t number_dimensions, const size_t *dimensions_sizes)
+{
+	struct lttng_counter *counter = NULL;
+	struct lttng_counter_transport *counter_transport = NULL;
+
+	counter_transport = lttng_counter_transport_find(counter_transport_name);
+	if (!counter_transport) {
+		printk(KERN_WARNING "LTTng: counter transport %s not found.\n",
+		       counter_transport_name);
+		goto notransport;
+	}
+	if (!try_module_get(counter_transport->owner)) {
+		printk(KERN_WARNING "LTTng: Can't lock counter transport module.\n");
+		goto notransport;
+	}
+
+	counter = lttng_kvzalloc(sizeof(struct lttng_counter), GFP_KERNEL);
+	if (!counter)
+		goto nomem;
+
+	/* Create event notifier error counter. */
+	counter->ops = &counter_transport->ops;
+	counter->transport = counter_transport;
+
+	counter->counter = counter->ops->counter_create(
+			number_dimensions, dimensions_sizes, 0);
+	if (!counter->counter) {
+		goto create_error;
+	}
+
+	return counter;
+
+create_error:
+	lttng_kvfree(counter);
+nomem:
+	if (counter_transport)
+		module_put(counter_transport->owner);
+notransport:
+	return NULL;
+}
+
+struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
+{
+	struct lttng_transport *transport = NULL;
+	struct lttng_event_notifier_group *event_notifier_group;
+	const char *transport_name = "relay-event-notifier";
+	size_t subbuf_size = 4096;	//TODO
+	size_t num_subbuf = 16;		//TODO
+	unsigned int switch_timer_interval = 0;
+	unsigned int read_timer_interval = 0;
+	int i;
+
+	mutex_lock(&sessions_mutex);
+
+	transport = lttng_transport_find(transport_name);
+	if (!transport) {
+		printk(KERN_WARNING "LTTng: transport %s not found\n",
+		       transport_name);
+		goto notransport;
+	}
+	if (!try_module_get(transport->owner)) {
+		printk(KERN_WARNING "LTTng: Can't lock transport %s module.\n",
+		       transport_name);
+		goto notransport;
+	}
+
+	event_notifier_group = lttng_kvzalloc(sizeof(struct lttng_event_notifier_group),
+				       GFP_KERNEL);
+	if (!event_notifier_group)
+		goto nomem;
+
+	/*
+	 * Initialize the ring buffer used to store event notifier
+	 * notifications.
+	 */
+	event_notifier_group->ops = &transport->ops;
+	event_notifier_group->chan = transport->ops.channel_create(
+			transport_name, event_notifier_group, NULL,
+			subbuf_size, num_subbuf, switch_timer_interval,
+			read_timer_interval);
+	if (!event_notifier_group->chan)
+		goto create_error;
+
+	event_notifier_group->transport = transport;
+
+	INIT_LIST_HEAD(&event_notifier_group->enablers_head);
+	INIT_LIST_HEAD(&event_notifier_group->event_notifiers_head);
+	for (i = 0; i < LTTNG_EVENT_NOTIFIER_HT_SIZE; i++)
+		INIT_HLIST_HEAD(&event_notifier_group->event_notifiers_ht.table[i]);
+
+	list_add(&event_notifier_group->node, &event_notifier_groups);
+
+	mutex_unlock(&sessions_mutex);
+
+	return event_notifier_group;
+
+create_error:
+	lttng_kvfree(event_notifier_group);
+nomem:
+	if (transport)
+		module_put(transport->owner);
+notransport:
+	mutex_unlock(&sessions_mutex);
+	return NULL;
+}
+
 void metadata_cache_destroy(struct kref *kref)
 {
 	struct lttng_metadata_cache *cache =
@@ -197,7 +337,7 @@ void lttng_session_destroy(struct lttng_session *session)
 	mutex_lock(&sessions_mutex);
 	WRITE_ONCE(session->active, 0);
 	list_for_each_entry(chan, &session->chan, list) {
-		ret = lttng_syscalls_unregister(chan);
+		ret = lttng_syscalls_unregister_event(chan);
 		WARN_ON(ret);
 	}
 	list_for_each_entry(event, &session->events, list) {
@@ -206,7 +346,7 @@ void lttng_session_destroy(struct lttng_session *session)
 	}
 	synchronize_trace();	/* Wait for in-flight events to complete */
 	list_for_each_entry(chan, &session->chan, list) {
-		ret = lttng_syscalls_destroy(chan);
+		ret = lttng_syscalls_destroy_event(chan);
 		WARN_ON(ret);
 	}
 	list_for_each_entry_safe(event_enabler, tmp_event_enabler,
@@ -234,6 +374,58 @@ void lttng_session_destroy(struct lttng_session *session)
 	lttng_kvfree(session);
 }
 
+void lttng_event_notifier_group_destroy(
+		struct lttng_event_notifier_group *event_notifier_group)
+{
+	struct lttng_event_notifier_enabler *event_notifier_enabler, *tmp_event_notifier_enabler;
+	struct lttng_event_notifier *event_notifier, *tmpevent_notifier;
+	int ret;
+
+	if (!event_notifier_group)
+		return;
+
+	mutex_lock(&sessions_mutex);
+
+	ret = lttng_syscalls_unregister_event_notifier(event_notifier_group);
+	WARN_ON(ret);
+
+	list_for_each_entry_safe(event_notifier, tmpevent_notifier,
+			&event_notifier_group->event_notifiers_head, list) {
+		ret = _lttng_event_notifier_unregister(event_notifier);
+		WARN_ON(ret);
+	}
+
+	/* Wait for in-flight event notifier to complete */
+	synchronize_trace();
+
+	irq_work_sync(&event_notifier_group->wakeup_pending);
+
+	kfree(event_notifier_group->sc_filter);
+
+	list_for_each_entry_safe(event_notifier_enabler, tmp_event_notifier_enabler,
+			&event_notifier_group->enablers_head, node)
+		lttng_event_notifier_enabler_destroy(event_notifier_enabler);
+
+	list_for_each_entry_safe(event_notifier, tmpevent_notifier,
+			&event_notifier_group->event_notifiers_head, list)
+		_lttng_event_notifier_destroy(event_notifier);
+
+	if (event_notifier_group->error_counter) {
+		struct lttng_counter *error_counter = event_notifier_group->error_counter;
+		error_counter->ops->counter_destroy(error_counter->counter);
+		module_put(error_counter->transport->owner);
+		lttng_kvfree(error_counter);
+		event_notifier_group->error_counter = NULL;
+	}
+
+	event_notifier_group->ops->channel_destroy(event_notifier_group->chan);
+	module_put(event_notifier_group->transport->owner);
+	list_del(&event_notifier_group->node);
+
+	mutex_unlock(&sessions_mutex);
+	lttng_kvfree(event_notifier_group);
+}
+
 int lttng_session_statedump(struct lttng_session *session)
 {
 	int ret;
@@ -479,15 +671,64 @@ end:
 	return ret;
 }
 
-static struct lttng_transport *lttng_transport_find(const char *name)
+int lttng_event_notifier_enable(struct lttng_event_notifier *event_notifier)
 {
-	struct lttng_transport *transport;
+	int ret = 0;
 
-	list_for_each_entry(transport, &lttng_transport_list, node) {
-		if (!strcmp(transport->name, name))
-			return transport;
+	mutex_lock(&sessions_mutex);
+	if (event_notifier->enabled) {
+		ret = -EEXIST;
+		goto end;
 	}
-	return NULL;
+	switch (event_notifier->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+	case LTTNG_KERNEL_SYSCALL:
+		ret = -EINVAL;
+		break;
+	case LTTNG_KERNEL_KPROBE:
+	case LTTNG_KERNEL_UPROBE:
+		WRITE_ONCE(event_notifier->enabled, 1);
+		break;
+	case LTTNG_KERNEL_FUNCTION:
+	case LTTNG_KERNEL_NOOP:
+	case LTTNG_KERNEL_KRETPROBE:
+	default:
+		WARN_ON_ONCE(1);
+		ret = -EINVAL;
+	}
+end:
+	mutex_unlock(&sessions_mutex);
+	return ret;
+}
+
+int lttng_event_notifier_disable(struct lttng_event_notifier *event_notifier)
+{
+	int ret = 0;
+
+	mutex_lock(&sessions_mutex);
+	if (!event_notifier->enabled) {
+		ret = -EEXIST;
+		goto end;
+	}
+	switch (event_notifier->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+	case LTTNG_KERNEL_SYSCALL:
+		ret = -EINVAL;
+		break;
+	case LTTNG_KERNEL_KPROBE:
+	case LTTNG_KERNEL_UPROBE:
+		WRITE_ONCE(event_notifier->enabled, 0);
+		break;
+	case LTTNG_KERNEL_FUNCTION:
+	case LTTNG_KERNEL_NOOP:
+	case LTTNG_KERNEL_KRETPROBE:
+	default:
+		WARN_ON_ONCE(1);
+		ret = -EINVAL;
+	}
+end:
+	mutex_unlock(&sessions_mutex);
+	return ret;
 }
 
 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
@@ -582,6 +823,7 @@ void _lttng_metadata_channel_hangup(struct lttng_metadata_stream *stream)
 	wake_up_interruptible(&stream->read_wait);
 }
 
+
 /*
  * Supports event creation while tracing session is active.
  * Needs to be called with sessions mutex held.
@@ -596,8 +838,6 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 	struct lttng_event *event;
 	const char *event_name;
 	struct hlist_head *head;
-	size_t name_len;
-	uint32_t hash;
 	int ret;
 
 	if (chan->free_event_id == -1U) {
@@ -622,9 +862,9 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 		ret = -EINVAL;
 		goto type_error;
 	}
-	name_len = strlen(event_name);
-	hash = jhash(event_name, name_len, 0);
-	head = &session->events_ht.table[hash & (LTTNG_EVENT_HT_SIZE - 1)];
+
+	head = utils_borrow_hash_table_bucket(session->events_ht.table,
+		LTTNG_EVENT_HT_SIZE, event_name);
 	lttng_hlist_for_each_entry(event, head, hlist) {
 		WARN_ON_ONCE(!event->desc);
 		if (!strncmp(event->desc->name, event_name,
@@ -645,7 +885,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 	event->id = chan->free_event_id++;
 	event->instrumentation = itype;
 	event->evtype = LTTNG_TYPE_EVENT;
-	INIT_LIST_HEAD(&event->bytecode_runtime_head);
+	INIT_LIST_HEAD(&event->filter_bytecode_runtime_head);
 	INIT_LIST_HEAD(&event->enablers_ref_head);
 
 	switch (itype) {
@@ -653,7 +893,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 		/* Event will be enabled by enabler sync. */
 		event->enabled = 0;
 		event->registered = 0;
-		event->desc = lttng_event_get(event_name);
+		event->desc = lttng_event_desc_get(event_name);
 		if (!event->desc) {
 			ret = -ENOENT;
 			goto register_error;
@@ -673,7 +913,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 		 * registration.
 		 */
 		smp_wmb();
-		ret = lttng_kprobes_register(event_name,
+		ret = lttng_kprobes_register_event(event_name,
 				event_param->u.kprobe.symbol_name,
 				event_param->u.kprobe.offset,
 				event_param->u.kprobe.addr,
@@ -789,7 +1029,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
 		 */
 		smp_wmb();
 
-		ret = lttng_uprobes_register(event_param->name,
+		ret = lttng_uprobes_register_event(event_param->name,
 				event_param->u.uprobe.fd,
 				event);
 		if (ret)
@@ -823,6 +1063,235 @@ full:
 	return ERR_PTR(ret);
 }
 
+struct lttng_event_notifier *_lttng_event_notifier_create(
+		const struct lttng_event_desc *event_desc,
+		uint64_t token, uint64_t error_counter_index,
+		struct lttng_event_notifier_group *event_notifier_group,
+		struct lttng_kernel_event_notifier *event_notifier_param,
+		void *filter, enum lttng_kernel_instrumentation itype)
+{
+	struct lttng_event_notifier *event_notifier;
+	const char *event_name;
+	struct hlist_head *head;
+	int ret;
+
+	switch (itype) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		event_name = event_desc->name;
+		break;
+	case LTTNG_KERNEL_KPROBE:
+	case LTTNG_KERNEL_UPROBE:
+	case LTTNG_KERNEL_SYSCALL:
+		event_name = event_notifier_param->event.name;
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+	case LTTNG_KERNEL_FUNCTION:
+	case LTTNG_KERNEL_NOOP:
+	default:
+		WARN_ON_ONCE(1);
+		ret = -EINVAL;
+		goto type_error;
+	}
+
+	head = utils_borrow_hash_table_bucket(event_notifier_group->event_notifiers_ht.table,
+		LTTNG_EVENT_NOTIFIER_HT_SIZE, event_name);
+	lttng_hlist_for_each_entry(event_notifier, head, hlist) {
+		WARN_ON_ONCE(!event_notifier->desc);
+		if (!strncmp(event_notifier->desc->name, event_name,
+					LTTNG_KERNEL_SYM_NAME_LEN - 1)
+				&& event_notifier_group == event_notifier->group
+				&& token == event_notifier->user_token) {
+			ret = -EEXIST;
+			goto exist;
+		}
+	}
+
+	event_notifier = kmem_cache_zalloc(event_notifier_cache, GFP_KERNEL);
+	if (!event_notifier) {
+		ret = -ENOMEM;
+		goto cache_error;
+	}
+
+	event_notifier->group = event_notifier_group;
+	event_notifier->user_token = token;
+	event_notifier->error_counter_index = error_counter_index;
+	event_notifier->num_captures = 0;
+	event_notifier->filter = filter;
+	event_notifier->instrumentation = itype;
+	event_notifier->evtype = LTTNG_TYPE_EVENT;
+	event_notifier->send_notification = lttng_event_notifier_notification_send;
+	INIT_LIST_HEAD(&event_notifier->filter_bytecode_runtime_head);
+	INIT_LIST_HEAD(&event_notifier->capture_bytecode_runtime_head);
+	INIT_LIST_HEAD(&event_notifier->enablers_ref_head);
+
+	switch (itype) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		/* Event will be enabled by enabler sync. */
+		event_notifier->enabled = 0;
+		event_notifier->registered = 0;
+		event_notifier->desc = lttng_event_desc_get(event_name);
+		if (!event_notifier->desc) {
+			ret = -ENOENT;
+			goto register_error;
+		}
+		/* Populate lttng_event_notifier structure before event registration. */
+		smp_wmb();
+		break;
+	case LTTNG_KERNEL_KPROBE:
+		/*
+		 * Needs to be explicitly enabled after creation, since
+		 * we may want to apply filters.
+		 */
+		event_notifier->enabled = 0;
+		event_notifier->registered = 1;
+		/*
+		 * Populate lttng_event_notifier structure before event
+		 * registration.
+		 */
+		smp_wmb();
+		ret = lttng_kprobes_register_event_notifier(
+				event_notifier_param->event.u.kprobe.symbol_name,
+				event_notifier_param->event.u.kprobe.offset,
+				event_notifier_param->event.u.kprobe.addr,
+				event_notifier);
+		if (ret) {
+			ret = -EINVAL;
+			goto register_error;
+		}
+		ret = try_module_get(event_notifier->desc->owner);
+		WARN_ON_ONCE(!ret);
+		break;
+	case LTTNG_KERNEL_NOOP:
+	case LTTNG_KERNEL_SYSCALL:
+		/*
+		 * Needs to be explicitly enabled after creation, since
+		 * we may want to apply filters.
+		 */
+		event_notifier->enabled = 0;
+		event_notifier->registered = 0;
+		event_notifier->desc = event_desc;
+		switch (event_notifier_param->event.u.syscall.entryexit) {
+		case LTTNG_KERNEL_SYSCALL_ENTRYEXIT:
+			ret = -EINVAL;
+			goto register_error;
+		case LTTNG_KERNEL_SYSCALL_ENTRY:
+			event_notifier->u.syscall.entryexit = LTTNG_SYSCALL_ENTRY;
+			break;
+		case LTTNG_KERNEL_SYSCALL_EXIT:
+			event_notifier->u.syscall.entryexit = LTTNG_SYSCALL_EXIT;
+			break;
+		}
+		switch (event_notifier_param->event.u.syscall.abi) {
+		case LTTNG_KERNEL_SYSCALL_ABI_ALL:
+			ret = -EINVAL;
+			goto register_error;
+		case LTTNG_KERNEL_SYSCALL_ABI_NATIVE:
+			event_notifier->u.syscall.abi = LTTNG_SYSCALL_ABI_NATIVE;
+			break;
+		case LTTNG_KERNEL_SYSCALL_ABI_COMPAT:
+			event_notifier->u.syscall.abi = LTTNG_SYSCALL_ABI_COMPAT;
+			break;
+		}
+
+		if (!event_notifier->desc) {
+			ret = -EINVAL;
+			goto register_error;
+		}
+		break;
+	case LTTNG_KERNEL_UPROBE:
+		/*
+		 * Needs to be explicitly enabled after creation, since
+		 * we may want to apply filters.
+		 */
+		event_notifier->enabled = 0;
+		event_notifier->registered = 1;
+
+		/*
+		 * Populate lttng_event_notifier structure before
+		 * event_notifier registration.
+		 */
+		smp_wmb();
+
+		ret = lttng_uprobes_register_event_notifier(
+				event_notifier_param->event.name,
+				event_notifier_param->event.u.uprobe.fd,
+				event_notifier);
+		if (ret)
+			goto register_error;
+		ret = try_module_get(event_notifier->desc->owner);
+		WARN_ON_ONCE(!ret);
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+	case LTTNG_KERNEL_FUNCTION:
+	default:
+		WARN_ON_ONCE(1);
+		ret = -EINVAL;
+		goto register_error;
+	}
+
+	list_add(&event_notifier->list, &event_notifier_group->event_notifiers_head);
+	hlist_add_head(&event_notifier->hlist, head);
+
+	/*
+	 * Clear the error counter bucket. The sessiond keeps track of which
+	 * bucket is currently in use. We trust it.
+	 */
+	if (event_notifier_group->error_counter) {
+		size_t dimension_index[1];
+
+		/*
+		 * Check that the index is within the boundary of the counter.
+		 */
+		if (event_notifier->error_counter_index >= event_notifier_group->error_counter_len) {
+			printk(KERN_INFO "LTTng: event_notifier: Error counter index out-of-bound: counter-len=%zu, index=%llu\n",
+				event_notifier_group->error_counter_len, event_notifier->error_counter_index);
+			ret = -EINVAL;
+			goto register_error;
+		}
+
+		dimension_index[0] = event_notifier->error_counter_index;
+		ret = event_notifier_group->error_counter->ops->counter_clear(
+				event_notifier_group->error_counter->counter,
+				dimension_index);
+		if (ret) {
+			printk(KERN_INFO "LTTng: event_notifier: Unable to clear error counter bucket %llu\n",
+				event_notifier->error_counter_index);
+			goto register_error;
+		}
+	}
+
+	return event_notifier;
+
+register_error:
+	kmem_cache_free(event_notifier_cache, event_notifier);
+cache_error:
+exist:
+type_error:
+	return ERR_PTR(ret);
+}
+
+int lttng_kernel_counter_read(struct lttng_counter *counter,
+		const size_t *dim_indexes, int32_t cpu,
+		int64_t *val, bool *overflow, bool *underflow)
+{
+	return counter->ops->counter_read(counter->counter, dim_indexes,
+			cpu, val, overflow, underflow);
+}
+
+int lttng_kernel_counter_aggregate(struct lttng_counter *counter,
+		const size_t *dim_indexes, int64_t *val,
+		bool *overflow, bool *underflow)
+{
+	return counter->ops->counter_aggregate(counter->counter, dim_indexes,
+			val, overflow, underflow);
+}
+
+int lttng_kernel_counter_clear(struct lttng_counter *counter,
+		const size_t *dim_indexes)
+{
+	return counter->ops->counter_clear(counter->counter, dim_indexes);
+}
+
 struct lttng_event *lttng_event_create(struct lttng_channel *chan,
 				struct lttng_kernel_event *event_param,
 				void *filter,
@@ -838,6 +1307,23 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
 	return event;
 }
 
+struct lttng_event_notifier *lttng_event_notifier_create(
+		const struct lttng_event_desc *event_desc,
+		uint64_t id, uint64_t error_counter_index,
+		struct lttng_event_notifier_group *event_notifier_group,
+		struct lttng_kernel_event_notifier *event_notifier_param,
+		void *filter, enum lttng_kernel_instrumentation itype)
+{
+	struct lttng_event_notifier *event_notifier;
+
+	mutex_lock(&sessions_mutex);
+	event_notifier = _lttng_event_notifier_create(event_desc, id,
+		error_counter_index, event_notifier_group,
+		event_notifier_param, filter, itype);
+	mutex_unlock(&sessions_mutex);
+	return event_notifier;
+}
+
 /* Only used for tracepoints for now. */
 static
 void register_event(struct lttng_event *event)
@@ -856,7 +1342,7 @@ void register_event(struct lttng_event *event)
 						  event);
 		break;
 	case LTTNG_KERNEL_SYSCALL:
-		ret = lttng_syscall_filter_enable(event->chan, event);
+		ret = lttng_syscall_filter_enable_event(event->chan, event);
 		break;
 	case LTTNG_KERNEL_KPROBE:
 	case LTTNG_KERNEL_UPROBE:
@@ -891,7 +1377,7 @@ int _lttng_event_unregister(struct lttng_event *event)
 						  event);
 		break;
 	case LTTNG_KERNEL_KPROBE:
-		lttng_kprobes_unregister(event);
+		lttng_kprobes_unregister_event(event);
 		ret = 0;
 		break;
 	case LTTNG_KERNEL_KRETPROBE:
@@ -899,13 +1385,13 @@ int _lttng_event_unregister(struct lttng_event *event)
 		ret = 0;
 		break;
 	case LTTNG_KERNEL_SYSCALL:
-		ret = lttng_syscall_filter_disable(event->chan, event);
+		ret = lttng_syscall_filter_disable_event(event->chan, event);
 		break;
 	case LTTNG_KERNEL_NOOP:
 		ret = 0;
 		break;
 	case LTTNG_KERNEL_UPROBE:
-		lttng_uprobes_unregister(event);
+		lttng_uprobes_unregister_event(event);
 		ret = 0;
 		break;
 	case LTTNG_KERNEL_FUNCTION:	/* Fall-through */
@@ -917,6 +1403,79 @@ int _lttng_event_unregister(struct lttng_event *event)
 	return ret;
 }
 
+/* Only used for tracepoints for now. */
+static
+void register_event_notifier(struct lttng_event_notifier *event_notifier)
+{
+	const struct lttng_event_desc *desc;
+	int ret = -EINVAL;
+
+	if (event_notifier->registered)
+		return;
+
+	desc = event_notifier->desc;
+	switch (event_notifier->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		ret = lttng_wrapper_tracepoint_probe_register(desc->kname,
+						  desc->event_notifier_callback,
+						  event_notifier);
+		break;
+	case LTTNG_KERNEL_SYSCALL:
+		ret = lttng_syscall_filter_enable_event_notifier(event_notifier);
+		break;
+	case LTTNG_KERNEL_KPROBE:
+	case LTTNG_KERNEL_UPROBE:
+		ret = 0;
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+	case LTTNG_KERNEL_FUNCTION:
+	case LTTNG_KERNEL_NOOP:
+	default:
+		WARN_ON_ONCE(1);
+	}
+	if (!ret)
+		event_notifier->registered = 1;
+}
+
+static
+int _lttng_event_notifier_unregister(
+		struct lttng_event_notifier *event_notifier)
+{
+	const struct lttng_event_desc *desc;
+	int ret = -EINVAL;
+
+	if (!event_notifier->registered)
+		return 0;
+
+	desc = event_notifier->desc;
+	switch (event_notifier->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		ret = lttng_wrapper_tracepoint_probe_unregister(event_notifier->desc->kname,
+						  event_notifier->desc->event_notifier_callback,
+						  event_notifier);
+		break;
+	case LTTNG_KERNEL_KPROBE:
+		lttng_kprobes_unregister_event_notifier(event_notifier);
+		ret = 0;
+		break;
+	case LTTNG_KERNEL_UPROBE:
+		lttng_uprobes_unregister_event_notifier(event_notifier);
+		ret = 0;
+		break;
+	case LTTNG_KERNEL_SYSCALL:
+		ret = lttng_syscall_filter_disable_event_notifier(event_notifier);
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+	case LTTNG_KERNEL_FUNCTION:
+	case LTTNG_KERNEL_NOOP:
+	default:
+		WARN_ON_ONCE(1);
+	}
+	if (!ret)
+		event_notifier->registered = 0;
+	return ret;
+}
+
 /*
  * Only used internally at session destruction.
  */
@@ -925,11 +1484,11 @@ void _lttng_event_destroy(struct lttng_event *event)
 {
 	switch (event->instrumentation) {
 	case LTTNG_KERNEL_TRACEPOINT:
-		lttng_event_put(event->desc);
+		lttng_event_desc_put(event->desc);
 		break;
 	case LTTNG_KERNEL_KPROBE:
 		module_put(event->desc->owner);
-		lttng_kprobes_destroy_private(event);
+		lttng_kprobes_destroy_event_private(event);
 		break;
 	case LTTNG_KERNEL_KRETPROBE:
 		module_put(event->desc->owner);
@@ -940,7 +1499,7 @@ void _lttng_event_destroy(struct lttng_event *event)
 		break;
 	case LTTNG_KERNEL_UPROBE:
 		module_put(event->desc->owner);
-		lttng_uprobes_destroy_private(event);
+		lttng_uprobes_destroy_event_private(event);
 		break;
 	case LTTNG_KERNEL_FUNCTION:	/* Fall-through */
 	default:
@@ -951,6 +1510,36 @@ void _lttng_event_destroy(struct lttng_event *event)
 	kmem_cache_free(event_cache, event);
 }
 
+/*
+ * Only used internally at session destruction.
+ */
+static
+void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier)
+{
+	switch (event_notifier->instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		lttng_event_desc_put(event_notifier->desc);
+		break;
+	case LTTNG_KERNEL_KPROBE:
+		module_put(event_notifier->desc->owner);
+		lttng_kprobes_destroy_event_notifier_private(event_notifier);
+		break;
+	case LTTNG_KERNEL_NOOP:
+	case LTTNG_KERNEL_SYSCALL:
+		break;
+	case LTTNG_KERNEL_UPROBE:
+		module_put(event_notifier->desc->owner);
+		lttng_uprobes_destroy_event_notifier_private(event_notifier);
+		break;
+	case LTTNG_KERNEL_KRETPROBE:
+	case LTTNG_KERNEL_FUNCTION:
+	default:
+		WARN_ON_ONCE(1);
+	}
+	list_del(&event_notifier->list);
+	kmem_cache_free(event_notifier_cache, event_notifier);
+}
+
 struct lttng_id_tracker *get_tracker(struct lttng_session *session,
 		enum tracker_type tracker_type)
 {
@@ -1226,7 +1815,6 @@ int lttng_match_enabler_name(const char *desc_name,
 	return 1;
 }
 
-static
 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 		struct lttng_enabler *enabler)
 {
@@ -1292,7 +1880,7 @@ int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 			return -EINVAL;
 		}
 		switch (enabler->event_param.u.syscall.match) {
-		case LTTNG_SYSCALL_MATCH_NAME:
+		case LTTNG_KERNEL_SYSCALL_MATCH_NAME:
 			switch (enabler->format_type) {
 			case LTTNG_ENABLER_FORMAT_STAR_GLOB:
 				return lttng_match_enabler_star_glob(desc_name, enabler_name);
@@ -1302,7 +1890,7 @@ int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
 				return -EINVAL;
 			}
 			break;
-		case LTTNG_SYSCALL_MATCH_NR:
+		case LTTNG_KERNEL_SYSCALL_MATCH_NR:
 			return -EINVAL;	/* Not implemented. */
 		default:
 			return -EINVAL;
@@ -1330,6 +1918,23 @@ int lttng_event_enabler_match_event(struct lttng_event_enabler *event_enabler,
 		return 0;
 }
 
+static
+int lttng_event_notifier_enabler_match_event_notifier(struct lttng_event_notifier_enabler *event_notifier_enabler,
+		struct lttng_event_notifier *event_notifier)
+{
+	struct lttng_enabler *base_enabler = lttng_event_notifier_enabler_as_enabler(
+		event_notifier_enabler);
+
+	if (base_enabler->event_param.instrumentation != event_notifier->instrumentation)
+		return 0;
+	if (lttng_desc_match_enabler(event_notifier->desc, base_enabler)
+			&& event_notifier->group == event_notifier_enabler->group
+			&& event_notifier->user_token == event_notifier_enabler->base.user_token)
+		return 1;
+	else
+		return 0;
+}
+
 static
 struct lttng_enabler_ref *lttng_enabler_ref(
 		struct list_head *enablers_ref_list,
@@ -1341,13 +1946,68 @@ struct lttng_enabler_ref *lttng_enabler_ref(
 		if (enabler_ref->ref == enabler)
 			return enabler_ref;
 	}
-	return NULL;
+	return NULL;
+}
+
+static
+void lttng_create_tracepoint_event_if_missing(struct lttng_event_enabler *event_enabler)
+{
+	struct lttng_session *session = event_enabler->chan->session;
+	struct lttng_probe_desc *probe_desc;
+	const struct lttng_event_desc *desc;
+	int i;
+	struct list_head *probe_list;
+
+	probe_list = lttng_get_probe_list_head();
+	/*
+	 * For each probe event, if we find that a probe event matches
+	 * our enabler, create an associated lttng_event if not
+	 * already present.
+	 */
+	list_for_each_entry(probe_desc, probe_list, head) {
+		for (i = 0; i < probe_desc->nr_events; i++) {
+			int found = 0;
+			struct hlist_head *head;
+			struct lttng_event *event;
+
+			desc = probe_desc->event_desc[i];
+			if (!lttng_desc_match_enabler(desc,
+					lttng_event_enabler_as_enabler(event_enabler)))
+				continue;
+
+			/*
+			 * Check if already created.
+			 */
+			head = utils_borrow_hash_table_bucket(
+				session->events_ht.table, LTTNG_EVENT_HT_SIZE,
+				desc->name);
+			lttng_hlist_for_each_entry(event, head, hlist) {
+				if (event->desc == desc
+						&& event->chan == event_enabler->chan)
+					found = 1;
+			}
+			if (found)
+				continue;
+
+			/*
+			 * We need to create an event for this
+			 * event probe.
+			 */
+			event = _lttng_event_create(event_enabler->chan,
+					NULL, NULL, desc,
+					LTTNG_KERNEL_TRACEPOINT);
+			if (!event) {
+				printk(KERN_INFO "LTTng: Unable to create event %s\n",
+					probe_desc->event_desc[i]->name);
+			}
+		}
+	}
 }
 
 static
-void lttng_create_tracepoint_event_if_missing(struct lttng_event_enabler *event_enabler)
+void lttng_create_tracepoint_event_notifier_if_missing(struct lttng_event_notifier_enabler *event_notifier_enabler)
 {
-	struct lttng_session *session = event_enabler->chan->session;
+	struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
 	struct lttng_probe_desc *probe_desc;
 	const struct lttng_event_desc *desc;
 	int i;
@@ -1356,47 +2016,44 @@ void lttng_create_tracepoint_event_if_missing(struct lttng_event_enabler *event_
 	probe_list = lttng_get_probe_list_head();
 	/*
 	 * For each probe event, if we find that a probe event matches
-	 * our enabler, create an associated lttng_event if not
+	 * our enabler, create an associated lttng_event_notifier if not
 	 * already present.
 	 */
 	list_for_each_entry(probe_desc, probe_list, head) {
 		for (i = 0; i < probe_desc->nr_events; i++) {
 			int found = 0;
 			struct hlist_head *head;
-			const char *event_name;
-			size_t name_len;
-			uint32_t hash;
-			struct lttng_event *event;
+			struct lttng_event_notifier *event_notifier;
 
 			desc = probe_desc->event_desc[i];
 			if (!lttng_desc_match_enabler(desc,
-					lttng_event_enabler_as_enabler(event_enabler)))
+					lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
 				continue;
-			event_name = desc->name;
-			name_len = strlen(event_name);
 
 			/*
 			 * Check if already created.
 			 */
-			hash = jhash(event_name, name_len, 0);
-			head = &session->events_ht.table[hash & (LTTNG_EVENT_HT_SIZE - 1)];
-			lttng_hlist_for_each_entry(event, head, hlist) {
-				if (event->desc == desc
-						&& event->chan == event_enabler->chan)
+			head = utils_borrow_hash_table_bucket(
+				event_notifier_group->event_notifiers_ht.table,
+				LTTNG_EVENT_NOTIFIER_HT_SIZE, desc->name);
+			lttng_hlist_for_each_entry(event_notifier, head, hlist) {
+				if (event_notifier->desc == desc
+						&& event_notifier->user_token == event_notifier_enabler->base.user_token)
 					found = 1;
 			}
 			if (found)
 				continue;
 
 			/*
-			 * We need to create an event for this
-			 * event probe.
+			 * We need to create a event_notifier for this event probe.
 			 */
-			event = _lttng_event_create(event_enabler->chan,
-					NULL, NULL, desc,
-					LTTNG_KERNEL_TRACEPOINT);
-			if (!event) {
-				printk(KERN_INFO "LTTng: Unable to create event %s\n",
+			event_notifier = _lttng_event_notifier_create(desc,
+				event_notifier_enabler->base.user_token,
+				event_notifier_enabler->error_counter_index,
+				event_notifier_group, NULL, NULL,
+				LTTNG_KERNEL_TRACEPOINT);
+			if (IS_ERR(event_notifier)) {
+				printk(KERN_INFO "Unable to create event_notifier %s\n",
 					probe_desc->event_desc[i]->name);
 			}
 		}
@@ -1408,7 +2065,18 @@ void lttng_create_syscall_event_if_missing(struct lttng_event_enabler *event_ena
 {
 	int ret;
 
-	ret = lttng_syscalls_register(event_enabler->chan, NULL);
+	ret = lttng_syscalls_register_event(event_enabler->chan, NULL);
+	WARN_ON_ONCE(ret);
+}
+
+static
+void lttng_create_syscall_event_notifier_if_missing(struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+	int ret;
+
+	ret = lttng_syscalls_register_event_notifier(event_notifier_enabler, NULL);
+	WARN_ON_ONCE(ret);
+	ret = lttng_syscals_create_matching_event_notifiers(event_notifier_enabler, NULL);
 	WARN_ON_ONCE(ret);
 }
 
@@ -1449,7 +2117,7 @@ int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
 	if (base_enabler->event_param.instrumentation == LTTNG_KERNEL_SYSCALL &&
 			base_enabler->event_param.u.syscall.entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT &&
 			base_enabler->event_param.u.syscall.abi == LTTNG_KERNEL_SYSCALL_ABI_ALL &&
-			base_enabler->event_param.u.syscall.match == LTTNG_SYSCALL_MATCH_NAME &&
+			base_enabler->event_param.u.syscall.match == LTTNG_KERNEL_SYSCALL_MATCH_NAME &&
 			!strcmp(base_enabler->event_param.name, "*")) {
 		if (base_enabler->enabled)
 			WRITE_ONCE(chan->syscall_all, 1);
@@ -1486,14 +2154,106 @@ int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
 		 */
 		lttng_enabler_link_bytecode(event->desc,
 			lttng_static_ctx,
-			&event->bytecode_runtime_head,
-			lttng_event_enabler_as_enabler(event_enabler));
+			&event->filter_bytecode_runtime_head,
+			&lttng_event_enabler_as_enabler(event_enabler)->filter_bytecode_head);
 
 		/* TODO: merge event context. */
 	}
 	return 0;
 }
 
+/*
+ * Create struct lttng_event_notifier if it is missing and present in the list of
+ * tracepoint probes.
+ * Should be called with sessions mutex held.
+ */
+static
+void lttng_create_event_notifier_if_missing(struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+	switch (event_notifier_enabler->base.event_param.instrumentation) {
+	case LTTNG_KERNEL_TRACEPOINT:
+		lttng_create_tracepoint_event_notifier_if_missing(event_notifier_enabler);
+		break;
+	case LTTNG_KERNEL_SYSCALL:
+		lttng_create_syscall_event_notifier_if_missing(event_notifier_enabler);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+}
+
+/*
+ * Create event_notifiers associated with a event_notifier enabler (if not already present).
+ */
+static
+int lttng_event_notifier_enabler_ref_event_notifiers(
+		struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+	struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
+	struct lttng_enabler *base_enabler = lttng_event_notifier_enabler_as_enabler(event_notifier_enabler);
+	struct lttng_event_notifier *event_notifier;
+
+	if (base_enabler->event_param.instrumentation == LTTNG_KERNEL_SYSCALL &&
+			base_enabler->event_param.u.syscall.abi == LTTNG_KERNEL_SYSCALL_ABI_ALL &&
+			base_enabler->event_param.u.syscall.match == LTTNG_KERNEL_SYSCALL_MATCH_NAME &&
+			!strcmp(base_enabler->event_param.name, "*")) {
+
+		int enabled = base_enabler->enabled;
+		enum lttng_kernel_syscall_entryexit entryexit = base_enabler->event_param.u.syscall.entryexit;
+
+		if (entryexit == LTTNG_KERNEL_SYSCALL_ENTRY || entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT)
+			WRITE_ONCE(event_notifier_group->syscall_all_entry, enabled);
+
+		if (entryexit == LTTNG_KERNEL_SYSCALL_EXIT || entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT)
+			WRITE_ONCE(event_notifier_group->syscall_all_exit, enabled);
+
+	}
+
+	/* First ensure that probe event_notifiers are created for this enabler. */
+	lttng_create_event_notifier_if_missing(event_notifier_enabler);
+
+	/* Link the created event_notifier with its associated enabler. */
+	list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, list) {
+		struct lttng_enabler_ref *enabler_ref;
+
+		if (!lttng_event_notifier_enabler_match_event_notifier(event_notifier_enabler, event_notifier))
+			continue;
+
+		enabler_ref = lttng_enabler_ref(&event_notifier->enablers_ref_head,
+			lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
+		if (!enabler_ref) {
+			/*
+			 * If no backward ref, create it.
+			 * Add backward ref from event_notifier to enabler.
+			 */
+			enabler_ref = kzalloc(sizeof(*enabler_ref), GFP_KERNEL);
+			if (!enabler_ref)
+				return -ENOMEM;
+
+			enabler_ref->ref = lttng_event_notifier_enabler_as_enabler(
+				event_notifier_enabler);
+			list_add(&enabler_ref->node,
+				&event_notifier->enablers_ref_head);
+		}
+
+		/*
+		 * Link filter bytecodes if not linked yet.
+		 */
+		lttng_enabler_link_bytecode(event_notifier->desc,
+			lttng_static_ctx, &event_notifier->filter_bytecode_runtime_head,
+			&lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
+
+		/* Link capture bytecodes if not linked yet. */
+		lttng_enabler_link_bytecode(event_notifier->desc,
+			lttng_static_ctx, &event_notifier->capture_bytecode_runtime_head,
+			&event_notifier_enabler->capture_bytecode_head);
+
+		event_notifier->num_captures = event_notifier_enabler->num_captures;
+	}
+	return 0;
+}
+
 /*
  * Called at module load: connect the probe on all enablers matching
  * this event.
@@ -1508,6 +2268,39 @@ int lttng_fix_pending_events(void)
 	return 0;
 }
 
+static bool lttng_event_notifier_group_has_active_event_notifiers(
+		struct lttng_event_notifier_group *event_notifier_group)
+{
+	struct lttng_event_notifier_enabler *event_notifier_enabler;
+
+	list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head,
+			node) {
+		if (event_notifier_enabler->base.enabled)
+			return true;
+	}
+	return false;
+}
+
+bool lttng_event_notifier_active(void)
+{
+	struct lttng_event_notifier_group *event_notifier_group;
+
+	list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
+		if (lttng_event_notifier_group_has_active_event_notifiers(event_notifier_group))
+			return true;
+	}
+	return false;
+}
+
+int lttng_fix_pending_event_notifiers(void)
+{
+	struct lttng_event_notifier_group *event_notifier_group;
+
+	list_for_each_entry(event_notifier_group, &event_notifier_groups, node)
+		lttng_event_notifier_group_sync_enablers(event_notifier_group);
+	return 0;
+}
+
 struct lttng_event_enabler *lttng_event_enabler_create(
 		enum lttng_enabler_format_type format_type,
 		struct lttng_kernel_event *event_param,
@@ -1552,17 +2345,17 @@ int lttng_event_enabler_disable(struct lttng_event_enabler *event_enabler)
 }
 
 static
-int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
+int lttng_enabler_attach_filter_bytecode(struct lttng_enabler *enabler,
 		struct lttng_kernel_filter_bytecode __user *bytecode)
 {
-	struct lttng_filter_bytecode_node *bytecode_node;
+	struct lttng_bytecode_node *bytecode_node;
 	uint32_t bytecode_len;
 	int ret;
 
 	ret = get_user(bytecode_len, &bytecode->len);
 	if (ret)
 		return ret;
-	bytecode_node = kzalloc(sizeof(*bytecode_node) + bytecode_len,
+	bytecode_node = lttng_kvzalloc(sizeof(*bytecode_node) + bytecode_len,
 			GFP_KERNEL);
 	if (!bytecode_node)
 		return -ENOMEM;
@@ -1571,6 +2364,7 @@ int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 	if (ret)
 		goto error_free;
 
+	bytecode_node->type = LTTNG_BYTECODE_NODE_TYPE_FILTER;
 	bytecode_node->enabler = enabler;
 	/* Enforce length based on allocated size */
 	bytecode_node->bc.len = bytecode_len;
@@ -1579,15 +2373,15 @@ int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
 	return 0;
 
 error_free:
-	kfree(bytecode_node);
+	lttng_kvfree(bytecode_node);
 	return ret;
 }
 
-int lttng_event_enabler_attach_bytecode(struct lttng_event_enabler *event_enabler,
+int lttng_event_enabler_attach_filter_bytecode(struct lttng_event_enabler *event_enabler,
 		struct lttng_kernel_filter_bytecode __user *bytecode)
 {
 	int ret;
-	ret = lttng_enabler_attach_bytecode(
+	ret = lttng_enabler_attach_filter_bytecode(
 		lttng_event_enabler_as_enabler(event_enabler), bytecode);
 	if (ret)
 		goto error;
@@ -1605,7 +2399,7 @@ int lttng_event_add_callsite(struct lttng_event *event,
 
 	switch (event->instrumentation) {
 	case LTTNG_KERNEL_UPROBE:
-		return lttng_uprobes_add_callsite(event, callsite);
+		return lttng_uprobes_event_add_callsite(event, callsite);
 	default:
 		return -EINVAL;
 	}
@@ -1620,12 +2414,12 @@ int lttng_event_enabler_attach_context(struct lttng_event_enabler *event_enabler
 static
 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 {
-	struct lttng_filter_bytecode_node *filter_node, *tmp_filter_node;
+	struct lttng_bytecode_node *filter_node, *tmp_filter_node;
 
 	/* Destroy filter bytecode */
 	list_for_each_entry_safe(filter_node, tmp_filter_node,
 			&enabler->filter_bytecode_head, node) {
-		kfree(filter_node);
+		lttng_kvfree(filter_node);
 	}
 }
 
@@ -1641,6 +2435,156 @@ void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler)
 	kfree(event_enabler);
 }
 
+struct lttng_event_notifier_enabler *lttng_event_notifier_enabler_create(
+		struct lttng_event_notifier_group *event_notifier_group,
+		enum lttng_enabler_format_type format_type,
+		struct lttng_kernel_event_notifier *event_notifier_param)
+{
+	struct lttng_event_notifier_enabler *event_notifier_enabler;
+
+	event_notifier_enabler = kzalloc(sizeof(*event_notifier_enabler), GFP_KERNEL);
+	if (!event_notifier_enabler)
+		return NULL;
+
+	event_notifier_enabler->base.format_type = format_type;
+	INIT_LIST_HEAD(&event_notifier_enabler->base.filter_bytecode_head);
+	INIT_LIST_HEAD(&event_notifier_enabler->capture_bytecode_head);
+
+	event_notifier_enabler->error_counter_index = event_notifier_param->error_counter_index;
+	event_notifier_enabler->num_captures = 0;
+
+	memcpy(&event_notifier_enabler->base.event_param, &event_notifier_param->event,
+		sizeof(event_notifier_enabler->base.event_param));
+	event_notifier_enabler->base.evtype = LTTNG_TYPE_ENABLER;
+
+	event_notifier_enabler->base.enabled = 0;
+	event_notifier_enabler->base.user_token = event_notifier_param->event.token;
+	event_notifier_enabler->group = event_notifier_group;
+
+	mutex_lock(&sessions_mutex);
+	list_add(&event_notifier_enabler->node, &event_notifier_enabler->group->enablers_head);
+	lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+
+	mutex_unlock(&sessions_mutex);
+
+	return event_notifier_enabler;
+}
+
+int lttng_event_notifier_enabler_enable(
+		struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+	mutex_lock(&sessions_mutex);
+	lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 1;
+	lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+	mutex_unlock(&sessions_mutex);
+	return 0;
+}
+
+int lttng_event_notifier_enabler_disable(
+		struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+	mutex_lock(&sessions_mutex);
+	lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 0;
+	lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+	mutex_unlock(&sessions_mutex);
+	return 0;
+}
+
+int lttng_event_notifier_enabler_attach_filter_bytecode(
+		struct lttng_event_notifier_enabler *event_notifier_enabler,
+		struct lttng_kernel_filter_bytecode __user *bytecode)
+{
+	int ret;
+
+	ret = lttng_enabler_attach_filter_bytecode(
+		lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
+		bytecode);
+	if (ret)
+		goto error;
+
+	lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+	return 0;
+
+error:
+	return ret;
+}
+
+int lttng_event_notifier_enabler_attach_capture_bytecode(
+		struct lttng_event_notifier_enabler *event_notifier_enabler,
+		struct lttng_kernel_capture_bytecode __user *bytecode)
+{
+	struct lttng_bytecode_node *bytecode_node;
+	struct lttng_enabler *enabler =
+			lttng_event_notifier_enabler_as_enabler(event_notifier_enabler);
+	uint32_t bytecode_len;
+	int ret;
+
+	ret = get_user(bytecode_len, &bytecode->len);
+	if (ret)
+		return ret;
+
+	bytecode_node = lttng_kvzalloc(sizeof(*bytecode_node) + bytecode_len,
+			GFP_KERNEL);
+	if (!bytecode_node)
+		return -ENOMEM;
+
+	ret = copy_from_user(&bytecode_node->bc, bytecode,
+		sizeof(*bytecode) + bytecode_len);
+	if (ret)
+		goto error_free;
+
+	bytecode_node->type = LTTNG_BYTECODE_NODE_TYPE_CAPTURE;
+	bytecode_node->enabler = enabler;
+
+	/* Enforce length based on allocated size */
+	bytecode_node->bc.len = bytecode_len;
+	list_add_tail(&bytecode_node->node, &event_notifier_enabler->capture_bytecode_head);
+
+	event_notifier_enabler->num_captures++;
+
+	lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+	goto end;
+
+error_free:
+	lttng_kvfree(bytecode_node);
+end:
+	return ret;
+}
+
+int lttng_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+		struct lttng_kernel_event_callsite __user *callsite)
+{
+
+	switch (event_notifier->instrumentation) {
+	case LTTNG_KERNEL_UPROBE:
+		return lttng_uprobes_event_notifier_add_callsite(event_notifier,
+				callsite);
+	default:
+		return -EINVAL;
+	}
+}
+
+int lttng_event_notifier_enabler_attach_context(
+		struct lttng_event_notifier_enabler *event_notifier_enabler,
+		struct lttng_kernel_context *context_param)
+{
+	return -ENOSYS;
+}
+
+static
+void lttng_event_notifier_enabler_destroy(
+		struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+	if (!event_notifier_enabler) {
+		return;
+	}
+
+	list_del(&event_notifier_enabler->node);
+
+	lttng_enabler_destroy(lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
+	kfree(event_notifier_enabler);
+}
+
 /*
  * lttng_session_sync_event_enablers should be called just before starting a
  * session.
@@ -1712,8 +2656,8 @@ void lttng_session_sync_event_enablers(struct lttng_session *session)
 
 		/* Enable filters */
 		list_for_each_entry(runtime,
-				&event->bytecode_runtime_head, node)
-			lttng_filter_sync_state(runtime);
+				&event->filter_bytecode_runtime_head, node)
+			lttng_bytecode_filter_sync_state(runtime);
 	}
 }
 
@@ -1733,6 +2677,78 @@ void lttng_session_lazy_sync_event_enablers(struct lttng_session *session)
 	lttng_session_sync_event_enablers(session);
 }
 
+static
+void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group)
+{
+	struct lttng_event_notifier_enabler *event_notifier_enabler;
+	struct lttng_event_notifier *event_notifier;
+
+	list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head, node)
+		lttng_event_notifier_enabler_ref_event_notifiers(event_notifier_enabler);
+
+	/*
+	 * For each event_notifier, if at least one of its enablers is enabled,
+	 * we enable the event_notifier, else we disable it.
+	 */
+	list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, list) {
+		struct lttng_enabler_ref *enabler_ref;
+		struct lttng_bytecode_runtime *runtime;
+		int enabled = 0, has_enablers_without_bytecode = 0;
+
+		switch (event_notifier->instrumentation) {
+		case LTTNG_KERNEL_TRACEPOINT:
+		case LTTNG_KERNEL_SYSCALL:
+			/* Enable event_notifiers */
+			list_for_each_entry(enabler_ref,
+					&event_notifier->enablers_ref_head, node) {
+				if (enabler_ref->ref->enabled) {
+					enabled = 1;
+					break;
+				}
+			}
+			break;
+		default:
+			/* Not handled with sync. */
+			continue;
+		}
+
+		WRITE_ONCE(event_notifier->enabled, enabled);
+		/*
+		 * Sync tracepoint registration with event_notifier enabled
+		 * state.
+		 */
+		if (enabled) {
+			if (!event_notifier->registered)
+				register_event_notifier(event_notifier);
+		} else {
+			if (event_notifier->registered)
+				_lttng_event_notifier_unregister(event_notifier);
+		}
+
+		/* Check if has enablers without bytecode enabled */
+		list_for_each_entry(enabler_ref,
+				&event_notifier->enablers_ref_head, node) {
+			if (enabler_ref->ref->enabled
+					&& list_empty(&enabler_ref->ref->filter_bytecode_head)) {
+				has_enablers_without_bytecode = 1;
+				break;
+			}
+		}
+		event_notifier->has_enablers_without_bytecode =
+			has_enablers_without_bytecode;
+
+		/* Enable filters */
+		list_for_each_entry(runtime,
+				&event_notifier->filter_bytecode_runtime_head, node)
+			lttng_bytecode_filter_sync_state(runtime);
+
+		/* Enable captures */
+		list_for_each_entry(runtime,
+				&event_notifier->capture_bytecode_runtime_head, node)
+			lttng_bytecode_capture_sync_state(runtime);
+	}
+}
+
 /*
  * Serialize at most one packet worth of metadata into a metadata
  * channel.
@@ -2984,6 +4000,29 @@ void lttng_transport_unregister(struct lttng_transport *transport)
 }
 EXPORT_SYMBOL_GPL(lttng_transport_unregister);
 
+void lttng_counter_transport_register(struct lttng_counter_transport *transport)
+{
+	/*
+	 * Make sure no page fault can be triggered by the module about to be
+	 * registered. We deal with this here so we don't have to call
+	 * vmalloc_sync_mappings() in each module's init.
+	 */
+	wrapper_vmalloc_sync_mappings();
+
+	mutex_lock(&sessions_mutex);
+	list_add_tail(&transport->node, &lttng_counter_transport_list);
+	mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(lttng_counter_transport_register);
+
+void lttng_counter_transport_unregister(struct lttng_counter_transport *transport)
+{
+	mutex_lock(&sessions_mutex);
+	list_del(&transport->node);
+	mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(lttng_counter_transport_unregister);
+
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
 
 enum cpuhp_state lttng_hp_prepare;
@@ -3136,7 +4175,12 @@ static int __init lttng_events_init(void)
 	event_cache = KMEM_CACHE(lttng_event, 0);
 	if (!event_cache) {
 		ret = -ENOMEM;
-		goto error_kmem;
+		goto error_kmem_event;
+	}
+	event_notifier_cache = KMEM_CACHE(lttng_event_notifier, 0);
+	if (!event_notifier_cache) {
+		ret = -ENOMEM;
+		goto error_kmem_event_notifier;
 	}
 	ret = lttng_abi_init();
 	if (ret)
@@ -3170,8 +4214,10 @@ error_hotplug:
 error_logger:
 	lttng_abi_exit();
 error_abi:
+	kmem_cache_destroy(event_notifier_cache);
+error_kmem_event_notifier:
 	kmem_cache_destroy(event_cache);
-error_kmem:
+error_kmem_event:
 	lttng_tracepoint_exit();
 error_tp:
 	lttng_context_exit();
@@ -3206,6 +4252,7 @@ static void __exit lttng_events_exit(void)
 	list_for_each_entry_safe(session, tmpsession, &sessions, list)
 		lttng_session_destroy(session);
 	kmem_cache_destroy(event_cache);
+	kmem_cache_destroy(event_notifier_cache);
 	lttng_tracepoint_exit();
 	lttng_context_exit();
 	printk(KERN_NOTICE "LTTng: Unloaded modules v%s.%s.%s%s (%s)%s%s\n",